Multicolor offset screen printing apparatus

ABSTRACT

An apparatus for producing a multi-color image on an object by means of the known silk screen process, wherein there are a number of silk screens each with its own pattern, the number of screens being equal to the number of colors to be employed. Colored printing media is applied with its own doctor blade to an associated silk screen. An intermediate color carrier such as a belt or a plurality of rollers receives a colored image from each screen and applies the colored image in sequence to an article by rolling contact between the article and the intermediate belt or rollers.

[54] M-ULTICOLOR OFFSET SCREEN PRINTING APPARATUS [75] Inventor: Albert Koelschbach, Cologne- Lindenthal, Germany [73] Assignee: Werner Kammann, Westfalen, Germany [22] Filed: Mar. 31, 1970 [21] Appl. No.: 24,251

[30] Foreign Application Priority Data Apr. 5, 1969 Germany ..P 19 17 520.3

[52] US. Cl. ..10l/l24,101/35,101/38, 101/115 [51] Int. Cl. ..B4lf 15/10 [58] Field of Search ..ll/35, 36, 38, 39, 101/40,114,115,129,124,177, 217, 214, 215, 173

[56] References Cited UNITED STATES PATENTS 1,259,285 3/1918 Reeve ..l01/2l5 2,447,521 8/1948 Miller et a1..... 101/119 2,584,092 1/1952 Keller et a1. 101/38 R 3,263,606 8/1966 Poynter 101/177 3,276,358 10/1966 Lusher 101/129 3,587,455 6/1971 Childress ..101/ 3,245,341 4/1966 Childress et a1. ..l01/122 2,615,328 10/1952 Tenety l ..l01/38 R 2,846,946 8/1958 Schwarzberger ..l01/ll5 [451 May 29,1973

3,419,413 12/1968 Euforbia ..101/1 15 UX 2,652,771 9/1953 Fernandez.... ..101/38 3,102,469 /1963 Sherman 101/122 2,364,277 12/1944 Dey et a1. 101/121 3,229,627 l/1966 Pollitt 101/115 3,066,602 12/1962 Ichinose 101/1 15 3,404,624 10/1968 Proffitt, Jr ..101/40 2,153,453 4/1939 Schneider etal ..101/ 3,461,795 8/1969 Decker et a1. ..10l/1 14 X FOREIGN PATENTS OR APPLICATIONS 482,642 4/1938 Great Britain ..101/35 546,309 7/1942 Great Britain ..101/426 Primary Examiner-Edgar S. Burr Assistant Examiner-R. E. Suter AttorneySughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT An apparatus for producing a multi-color image on an object by means of the known silk screen process, wherein there are a number of silk screens each with its own pattern, the number of screens being equal to the number of colors to be employed. Colored printing media is applied with its own doctor blade to an associated silk screen. An intermediate color carrier such as a belt or a plurality of rollers receives a colored image from each screen and applies the colored image in sequence to an article by rolling contact between the articleand the intermediate belt or rollers.

1 Claim, 13 Drawing Figures PATENTEUHAYZSIQYS SHEET 3 [IF 4 1 MULTICOLOR OFFSET SCREEN PRINTING APPARATUS The invention relates to a multi-color screen printing process for printing a variety of articles, and an apparatus for carrying out this process.

It is an object of the invention to provide a multicolor screen printing process which allows various colors to be printed in one operation on a succession of articles. This process is intended to minimize the drying periods between the individual printing operations and to allow a satisfactory multi-color printing to be obtained.

A further object of the invention resides in providing a simple and compact apparatus for carrying out the process.

In accordance with the invention in a multi-color screen printing process individual colors are applied by juxtaposed screen printing devices simultaneously and at positions spaced apart on one or more intermediate color carriers and from there transmitted in a continuous operation in timed juxtaposition on to articles to be printed.

The process in accordance with the invention does not apply the colors one on top of the other but side by side on the intermediate color carrier, so as to obviate the-danger of smudging.

The intermediate color carrier is formed as an endless belt or a plurality of rollers. The endless belt is preferably used for printing cylindrical articles such as bottles, and the rollers for printing flat surfaces. During transfer of-the color from the intermediate color carrier to the article, the two bodies are in rolling engagement with one another this ensures a clean transfer of color.

When using rollers as intermediate color carriers, one color at a time is applied to each roller, and the rollers are successively rolled over the article. When using a belt as an intermediate color carrier, the different colors are applied to points of the belt spaced apart and subsequently the article is rolled over the belt.

The invention preferably uses a color medium having a short drying period, so that the color medium is transferred from the intermediate color carrier to the article without smudging.

According to a feature of the invention, the intermediate color carrier is provided with a rubber coating. With such an intermediate color carrier, the color medium does not form a bond. The ink becomes partially solidified while still on the intermediate ink carrier, and forms a film which during the rolling engagement between the intermediate ink carrier and the article is transferred thereto; then the color film forms a firm bond with the article.

In accordance with the invention an apparatus for carrying out the multi-color printing process is such that a plurality of screen printing frames corresponding in number to the number of colors are arranged in series and interconnected, each screen printing frame having a doctor associated therewith interconnected by means of a bar, and also rollers -in contact with the screens, each roller being associated with one screen printing frame, the rollers being interconnected via a bar for mutual movement, the screen printing frames being displaceable relative to the doctors and rollers, and the rollers relative to the screen printing frames,

there being a retaining member for the article to be printed on the roller train.

The screen printing frames may be connected with a toothed rack each roller meshing with the rack by means of a gear wheel. The engagement of the gear wheels in the teeth of the bar ensures that the rollers rotate in synchronism and thus apply the color at the required point of the article accurately. Stop and drive devices are provided for the bars which interconnect the screen printing frames and the rollers. The screen printing frames are moved to ink the rollers and to transfer the ink to the article to be printed, the rollers are moved and rolled over the article; one bar at a time is displaced, while the other is locked.

A further feature of the invention is to provide an endlessbelt as an intermediate carrier, which is passed over two guide rollers and having its upper belt section in contact with the screen printing frame a device on its lower belt section is adapted to press the article to be printed against the belt.

The screen printing frames are adapted to be removable from the belt.

The multi-color printing is effected substantially simultaneously in one pass of the article to be printed, resulting in a very high speed of production.

Since the articles to be printed only pass once through the apparatus, faulty impressions are substantially reduced and hence manufacturing costs are also reduced.

All color impressions occur at the predetermined points. The process ensures accurate printing of a variety of articles. The apparatus for carrying out the process is simple and compact in structure and may be operated by a single operator.

Examples of the invention are shown in the drawings, in which:

FIG. 1 is a schematic view of a method of screen printing the beginning of a printing operation; for simplification printing with one color only is shown,

FIG. 2 is a similar view to FIG. 1 showing a printing operation after the intermediate ink carrier has been inked,

FIG. 3 is a similar view after ink transfer to the article to be printed,

FIG. 4 is a schematic view of an apparatus in accordance with the invention with three rollers at the beginning of a printing operation,

FIG. 5 is a schematic view of an identical apparatus after inking the rollers,

FIG. 6 shows an oval bottle as an article to be printed,

FIG. 7 is the apparatus shown in FIGS. 4 and 5 during ink transfer from the rollers onto the article to be printed,

FIG. 8 is a schematic view of the apparatus in accordance with the'invention showing the toothed engagementbetween rollers and screen printing frames at the beginning of the printing operation,

FIG. 9 is the same apparatus after the roller have been inked,

FIG. 10 is the same apparatus showing the movement of the rollers over the article to be printed,

FIG. 11 is a schematic view of an embodiment of the invention in which an endless belt is used as intermediate ink carrier; the apparatus is shown at the beginning of a printing operation,

FIG. 12 is the same apparatus after inking of the intermediate ink carrier or the endless belt respectively,

FIG. 13 is the same apparatus at the beginning of the ink transfer from the endless belt onto the article to be printed.

FIGS. 1-3 show a screen printing frame 10 of conventional form. The latter contains a frame 12. Below this frame 12 the gauze 14 is stretched. The printing form 16 is placed thereon. In the example shown, this is the letter H. A doctor blade 18 is mounted in the frame 12. These parts 10 18 and their mode of operation are of conventional construction and need not be further explained.

Below the screen printing frame 10 there is an intermediate ink carrier in the form of a roller 22. The latter comprises a resilient core 24, which is provided with a silicone rubber coating 26. The article to be printed is flat and denoted by 27.

As shown in FIG. 1, some ink 11 is located at the right hand lower edge of the doctor 18. To transfer this ink 11 to the roller 22 the screen printing frame 10 is displaced to the left. During this movement, the roller 22 is in rolling engagement over the underside thereof. An H is formed thereon, as shown in FIG. 2. As already explained, this H is smudge-resistant substantially immediately after its application to the roller, and has the form of a film-like application. During the next and last operational stage the roller 22 is rolled over the article 27, resulting in the image shown in FIG. 3. The roller has transferred the H to the article 28.

The principle of the invention has thus been explained by way of a reference to single color printing. For multi-color printing the screen printing frames, and rollers are connected in series. Three-color printing is described hereinafter. Two-color, or four-color printing is possible by means of the invention.

As an example of the article to be printed, FIG. 6 shows an oval bottle 28. This bottle 28 has a flat part so that it cannot roll itself. Consequently rollers which can be in rolling engagement over the bottle 28 can be used an an intermediate ink carrier. FIGS. 4, and 7 show a suitable apparatus. A three-colored image comprising a background 32, a central portion 34 and a crown 36 as foreground, is printed thereon. In the apparatus the bottle 28 is retained in a holder 38. The rollers 22 move along the bottle. A bar 40 carries the rollers 22 at suitable spacings. The doctors 18 are mounted on another bar 42. To make the three impressions 32, 34 and 36 the three screen printing frames have different printing forms 46, 48 and 50.

FIG. 4 shows the inoperative or starting position. During the first stage of the operation the screen printing frames are mutually shifted to the left. Their undersides slide over the rollers 22. Since these are retained by the bar 40, the rollers are in rolling engagement with the undersides of the screen printing frames 10. The ink is transferred to the rollers. This stage of the operation is shown in FIG. 5.

In the next operating stage the bar 40 is released. At the same time the screen printing frames 10 are lifted off the rollers 22, or the rollers are lowered. These movements may be carried out by any suitable means well-known in the printing art, such as scissor linkages, cam drives, chain drives, or other similar, well-known arrangements. The rollers 22 are subsequently moved to the left. They move along the underside of the article 28 and off of it, as seen in FIG. 7. Each roller transfers its ink application to the article 28. This image is shown in FIG. 6. The screen printing frames 10 have here been moved towards the right and assume their original position shown in FIG. 4.

FIGS. 8 10 correspond in principle to FIGS. 4, 5 and 7. These three figures show the synchronizing means for the individual elements. These ensure that the relative positions between screen printing frames and the rollers on the one hand and the rollers relative to the article to be printed on the other hand are maintained accurately. This in turn ensures that the colors are impressed on the article at the points required.

In this example the three screen printing frames 10 are mounted on a bar 41. On its underside this bar has a rack 54. Each roller 22 carries a gear wheel 56 on its end face. The gear wheels 56 mesh with the rack 54. In this schematic view a stop 58 is also provided. This stop 58 locks the bar 40 andprevents the rollers 22 from being engaged when the screen printing frames 10 are displaced. Stop 58 can be controlled by appropriate motor means 59.

FIG. 8 shows the start or original position. Each screen printing frame 10 applies a different color ink. Subsequently the bar 41 is displaced to the left by appropriate motor means 43. This is indicated by the arrow in FIG. 9. The rollers 22 or the bar 40 are unable to follow this movement, since the stop 58 presses against the end of the bar 40. The engagement between rack 54 and gear wheels 56 causes the rollers 22 to be in rolling engagement over the underside of the screen printing frames 10. One color at a time is transferred to each roller.

During the next stage of the operation the screen printing frames 10 with the doctors 18 are lifted up wards by appropriate motor means 45. This is indicated by the arrows in FIG. 10. Stop 58 is simultaneously pulled away downward. The bar 40 is then displaced to the left in the direction of the arrow by any appropriate mechanism, such as 47. It moves in a direction towards the article 28 to be printed, as shown in FIGS. 4, 5 and 7. The rollers 22 are in rolling engagement with the surface of the article and transfer their ink thereto.

FIGS. 11 13 show an embodiment used for applying printing to a curved surface, in which the article 29 to be printed is cylindrical and adapted to be in rolling engagement on an intermediate colored ink carrier. An endless belt 62 is passed around two guide rollers 64. The article 29 to be printed, such as cylindrical spray container, is supported on two supporting rollers 66. A pressure application roller 68, which is held by a spring element 70, presses the belt 62 resiliently against the article 29 to be printed. There is a cleaning roller 72 rests again-t the belt 62 downstream of the article.

FIG. 11 again shows the commencing or original position. The screen printing frames 10 are filled with ink. The doctors 18 are moved to the right in the direction of the arrows and transfer the ink to the belt 62. Subsequently, the screen printing frames 10 with the doctors 18 are raised. FIG. 12 shows the resulting images. Three ink applications 74, 76, 78 are located on the belt 62. The belt is now set in motion in a clockwise direction. This is shown in FIG. 13, which portrays the instant at which the first color application 78 arrives at the article 29 and is applied thereto. It has already been explained that the ink application, due to the silicone coating, adheres only loosely to the belt 62 and may be drawn off like a film. This now takes'place onto the article 29 to be printed. This article receives the film-like ink application and unwinds it thereon. When the article 29 has rotated once through 360, it has arrived at the next ink application position. This film-like ink application is also applied by rolling engagement over the article 29. The same occurs with the next and last ink application.

In exceptional cases, should the ink adhere to the belt 62, then it is removed by the cleaning roller 72, which contacts the surface-of belt 62 to remove excess ink from the belt surface by scraping, absorption, or other suitable means.

The above description has shown that the screen printing technique used makes possible a thick, covering ink application. The intermediate ink carrier further ensures that the different ink applications can be applied exactly one over the other or in one another onto the article to be printed. This is due to the fact that the article has to be passed only once through the apparatus, the accurate overprinting being ensured by the mechanism of the apparatus itself.

In addition to the printing of containers, tins, flasks etc., the process of the invention and the apparatus, are suitable for all purposes in which articles of all kinds have to be printed in several colors. A further field of application is printing on paper and cardboard, such as posters and display articles. In this case difficulties have hitherto been encountered when a large area of paper, such as a poster, had to be passed several times through the printing apparatus. It frequently occurred that the second, third or fourth application was displaced. Printing in accordance with the invention prevents these faults from occurring, since the poster is printed in several colors in one passage through the apparatus.

I claim:

l. A screen printing apparatus for printing articles 6 comprising:

a plurality of screen printing means, each screen printing means adapted for using a different color and indicia from that used by the others;

a plurality of intermediate color carriers, one color carrier for each screen printing means, said color carriers positioned beneath the screen printing means and in cooperative relationship therewith for receiving the indicia;

a toothed support member for said plurality of screen printing means;

a gear member arranged on each color carrier and operatively connected thereto, each of said color carriers comprising a silicone rubber coated roller, each gear member meshing with the toothed support member;

means for moving the toothed support member relative to the rollers to impart the color indicia from each of said plurality of screen printing means onto its corresponding roller;

stop means for selectively preventing movement of the rollers with said toothed support member and permitting a relative rolling engagement between the rollers and the screen printing means as the rollers receive their respective indicia;

means for lifting the screen printing means upward out of engagement with the respective rollers, and

means for moving the rollers relative to said toothed support member with engagement between the toothed support member and the roller gears, whereby the rollers can respectively impart their color indicia upon the article by a rolling engagement with said article. 

1. A screen printing apparatus for printing articles comprising: a plurality of screen printing means, each screen printing means adapted for using a different color and indicia from that used by the others; a plurality of intermediate color carriers, one color carrier for each screen printing means, said color carriers positioned beneath the screen printing means and in cooperative relationship therewith for receiving the indicia; a toothed support member for said plurality of screen printing means; a gear member arranged on each color carrier and operatively connected thereto, each of said color carriers comprising a silicone rubber coated roller, each gear member meshing with the toothed support member; means for moving the toothed support member relative to the rollers to impart the color indicia from each of said plurality of screen printing means onto its corresponding roller; stop means for selectively preventing movement of the rollers with said toothed support member and permitting a relative rolling engagement between the rollers and the screen printing means as the rollers receive their respective indicia; means for lifting the screen printing means upward out of engagement with the respective rollers, and means for moving the rollers relative to said toothed support member with engagement between the toothed support member and the roller gears, whereby the rollers can respectively impart their color indicia upon the article by a rolling engagement with said article. 